Immediately before birth, the gastro-intestinal tract of a baby is thought to be sterile. During the normal process of birth, it encounters bacteria from the digestive tract, skin and environment of the mother and starts to become colonised. The faecal microbiota of a healthy, vaginally-delivered, breast-fed infant of age 2 to 4 weeks which may be taken as the optimum microbiota for this age group is dominated by Bifidobacteria species with some Lactobacillus species and lesser amounts of Bacteroides such as Bacteriodes fragilis species, at the expense of potential pathogens such as Clostridia. After the completion of weaning at about 2 years of age, a pattern of gut microbiota that resembles the adult pattern becomes established.
It should be noted that, in the healthy, vaginally-delivered, breast-fed infant, Bifidobacteria form the basis of the microbiota accounting for 60-90% of total bacteria in the infant gut. Breast feeding also promotes intestinal barrier development which, together with bifidobacterial domination leads to enhanced absorption and therefore utilisation of ingested nutrition.
Grönlund et al have studied the faecal microbiota of healthy infants born by cesarean section and compared it with that of a comparable group of infants born by vaginal delivery. They concluded that the gut flora of infants born by cesarean delivery may be disturbed for up to six months after the birth. Specifically they noted that the rates of colonisation by Bifidobacteria and Lactobacilli in the cesarean group reached the rates of colonisation in the vaginally delivered group only after one month and ten days respectively (Grönlund et al, “Fecal Microflora in Healthy Infants Born by Different Methods of Delivery: Permanent Changes in Intestinal Flora After Cesarean Delivery”, Journal of Pediatric Gastroenterology and Nutrition, 28:19-25).
Other workers have suggested that this delayed/aberrant colonisation may have specific consequences in terms of the subsequent development of the infant and have investigated a possible link between these consequences and differences in the gut microbiota. For example, Martino et al investigated colonisation patterns and mucosal IgA production at 6 months of age in relation to early exposures, systemic immune development and early allergic outcomes in a cohort who had received either the probiotic Lactobacillus acidophilus strain LAVRI-A1 or a placebo (Martino et al, “Relationship between early intestinal colonisation, mucosal immunoglobulin A production and systemic immune development” Clinical and Experimental Allergy, 38, 69-78).
Mother's milk is recommended for all infants. However, in some cases breast feeding is inadequate or unsuccessful for medical reasons or the mother chooses not to breast feed. Infant formulae have been developed for these situations.
In the recent past, certain strains of bacteria have attracted considerable attention because they have been found to exhibit valuable properties for man if ingested. In particular, specific strains of the genera Lactobacilli and Bifidobacteria have been found to be able to colonise the intestine, to reduce the capability of pathogenic bacteria to adhere to the intestinal epithelium, to have immunomodulatory effects and to assist in the maintenance of well-being. Such bacteria are sometimes called probiotics and it has already been proposed to add suitable probiotic bacteria to infant formulas.
Extensive studies have been carried out to identify new probiotic strains. For example, EP 0 199 535, EP 0 768 375, WO 97/00078, EP 0 577 903 and WO 00/53200 disclose specific strains of Lactobacilli and Bifidobacteria and their beneficial effects.
For example, Vancikova et al reported that early artificial mucosal colonisation with the probiotic bacterial strain E. coli O83 stimulates the mucosal immune system to produce non-specific secretory IgA in addition to specific antibodies (Vancikova et al, “The early postnatal development of salivary antibody and immunoglobulin response in children orally colonised with a non-pathogenic, probiotic strain of E. coli” Folia Microbiol (Praha) 2003; 48:281-7).
Fukushima et al studied the effect of a probiotic Bifidobacterium lactis strain on IgA secretion in a cohort of older children (15 to 31 months old) and found increased levels of total IgA and anti-polio virus IgA.
The proportion of cesarean deliveries continues to increase reaching as much as 70% of all births in some countries. It is therefore clear that there is a need to provide a means to reduce the risk that infants born by cesarean section do not suffer adverse health consequences as a result of their mode of delivery. This need is particularly acute given the current practice of routinely administering prophylactic doses of antibiotics to pregnant women who undergo an elective cesarean delivery.